One mechanism by which fire may spread from one compartment of a structure to another is through passages or openings, often referred to as through-penetrations, in the floors and walls. Such openings include, for example, cable access holes through which signal and power transmission cables pass.
Current methods used to prevent the spread of fire and passage of smoke through such openings include cutting two intumescent sheets to follow the contour of the penetrating cables and providing a bead of moldable intumescent putty along the perimeter of each sheet. While this technique is generally satisfactory for resisting the spread of fire and preventing the passage of smoke from one compartment to another, installation is labor intensive and time consuming In addition, fire stops fabricated in this manner do not lend themselves to repeated re-entry.
Techniques and materials for fire stopping through-penetrations are known in the patented prior art. The Bailey U.S. Pat. No. 5,032,447, for example, discloses a fire barrier material, for use in building construction, comprising a sandwich structure having first and second outside layers comprising corrugated high temperature resistant metal and at least one intermediate layer comprising a flame retardant fibrous material, wherein the corrugations are positioned on the outside layers in an array which enables the barrier material to be folded in a direction substantially perpendicular to the corrugations.
The Knott et al. U.S. Pat. No. 5,402,615 discloses a flexible barrier for preventing the spread of fire through areas of a building that includes a layer of inorganic fibrous material sandwiched between two panels of material having sufficiently high thermal conductivity to diffuse and dissipate heat without burning when exposed to a flame. The panels and fibrous material are joined together with a filament having sufficiently high tensile strength and resistance to heat to maintain the panels and layers in laminar relation.
The Kiser U.S. Pat. No. 5,681,640 discloses a passive fire protection system for the protection of conduits, cable trays, support rods, and structural steel against flame and heat in a severe total environment type fire that includes a multi-layered, flexible material containing a plurality of layers of intumescent material.
In addition, various bag-like devices for fire stopping through-penetrations are commercially available. Each of these prior devices or techniques, however, suffer from certain drawbacks or shortcomings. For example, currently available products require secondary reinforcement structures to support the intumescent material in all but the smallest openings.
Accordingly, there exists a need in the industry for a fire stop device for fire stopping through-penetrations that is inexpensive, easy to install, and can effectively fire stop larger openings than conventional devices can without the need for a secondary support structure.